Open Protective Tube

ABSTRACT

The invention relates to an open protective tube consisting of a first layer ( 1 ) comprising a plurality of plastic threads which are woven to one another and a second layer of aluminium foil ( 2 ). The invention is characterised in that the aluminium foil layer ( 2 ) consists of a film of plastic material ( 3 ) and a film of aluminium ( 4 ). According to the invention, the plastic film ( 3 ) comprises polyester and said film is welded to the first layer ( 1 ). In this way, the invention provides excellent electromagnetic and thermal insulation, as well as excellent adhesion between the first and second layers.

The invention refers to an open protective tube, especially for the mechanical and thermal protection of electrical conducts and other components in automobiles.

BACKGROUND TO THE INVENTION

At the present time protection tubes are used to protect electrical conductors and other components, especially in the automobile industry.

These protection tubes must combine different characteristics that make them suitable for these types of uses.

In the first place, the protection tubes must have great mechanical and thermal resistance, as they are used in areas of high temperature and where they are subjected to abrasion.

In addition, these protection tubes must include noise insulation characteristics, as it would be unacceptable for these protection tubes to produce noise when used in automobiles.

In addition, these protective tubes must be easy to install.

In order to solve these disadvantages there are a great number of protection tubes that combine these characteristics and which are currently used to protect cables in automobiles.

One of the most important characteristics that these protection tubes must have is resistance to high temperatures. At the present time there are protective tubes formed by a series of layers, for example a first layer formed by a plurality of a plastic material or mineral threads knitted to one another and a second layer of aluminium film on said first layer. These protection tubes are used to achieve good electromagnetic and thermal insulation.

In this case, the fixing of the layer of aluminium film to the second layer with adhesive is currently known. These types of protective tube have the disadvantage that they cannot stand high temperatures due to the fact that the adhesives do not withstand high temperatures with the lack of suitable adherence between the aluminium film and the first previously stated layer.

DESCRIPTION OF THE INVENTION

With the open protection tube of the invention the stated disadvantages are resolved, presenting other advantages which will be described.

The open protective tube of the invention has a first layer comprising a plurality of plastic threads which are woven to one another and a second layer of aluminium foil, and is characterised in that the said aluminium foil comprises a plastic material film and an aluminium film, said plastic material film being welded to the stated first layer.

The protective tube is open along its length making the assembly significantly easier.

According to the preferred embodiment, said plastic material comprises polyester.

According to alternative embodiments, the threads that comprise the first layer are made from polyester or polyester and polyamide.

If required, the aluminium film can be located on the inner part of the tube.

With the protective tube of this present invention excellent electromagnetic and thermal insulation is achieved, supporting high temperatures, and excellent adherence between the first and second layers and with great ease in assembly.

A BRIEF DESCRIPTION OF THE DRAWINGS

In order to give a greater understanding of that which has been stated some drawings are included in which an outline of a practical embodiment is made which is made by way of being an example and without being by way of limitation.

FIG. 1 shows a transverse section view of the protective tube of the invention;

FIG. 2 is a graph in which the results of the trials are shown in order to demonstrate the electromagnetic insulation of the protective tube of this present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

As and how can be seen in the only figure, the protective tube of the invention is made up of two layers:

-   -   A first layer (1) comprising of a plurality of polyester or         polyester and polyamide threads that are woven to each other;         and     -   A second layer of aluminium foil (2) over said first layer (1).

The aluminium foil layer (2) is made from a polyester film (3) and an aluminium film (4), said polyester film (3) being welded to said first layer (1). For example, the thickness of the polyester layer (3) can be 23 microns and the thickness of the aluminium foil (4) can be from 9 to 25 microns, with a total weight for the aluminium layer (2) being 2.6 g/m.

The welding of the aluminium foil layer (2) on the first layer (1) is by preference made at a temperature of between 240° C. and 540° C. said welding being carried out with a continuous process at a speed of between 1 and 20 m/min.

Said first layer (1) has, for example, has a weight of 17.26 g/m and a thickness of 1.0 mm±0.3 mm for a width of 50 mm.

For example the tube of this present invention, can have a weight of 19.86 g/m and a thickness of 1.0 mm±0.3 mm for a diameter of 7 mm.

The order of the layers can be inverted placing the aluminium on the inside and the woven layer on the outside.

As has been previously stated, with the protective tube of the present invention excellent electromagnetic and thermal insulation is achieved, even at high temperatures.

In order to demonstrate this statement several trials have been carried out on the protective tube of this present invention.

In order to assess the electromagnetic insulation of the protective tube of the present invention a spectrum analyser (Agilent E-4402B) was used with an internal radio-frequency generator.

A two-metre long wire, connected to the generator acted as the electromagnetic wave transmitter. A screened coaxial cable, parallel to the wire separated by some 2 cm, and with a length of 15 cm without screening, acted as the aerial, and was connected to the spectrum analyser.

First, a measurement of the power received is carried out. After the 15 cm aerial is screened with the trial tube (sample) and the power received is again measured. The difference between both powers is a screening measurement of the sample.

It must be taken into account that the majority of measurements are of minimum screening, and that the real screening is always greater than that of the graphs. This is a consequence of the fact that the measurement with the screened aerial almost always gives a zero power received.

If the power transmitted were higher, or the sensitivity of the spectrum analyser were greater, measurements could be carried out in which the power received with the screening were different to zero, and therefore, maximum screening values will be the result.

The results of the trial are shown in the graph in FIG. 2.

In order to check the characteristics of the thermal insulation a trial was carried out. The main objective of this trial was to study the performance of the protection tube under an external heat source.

In this case, it is very important to control the ambient temperature whilst the trial is being carried out in order to obtain reliable performance. Depending on the ambient temperature, the thermal insulation results can change.

The trial was carried out in accordance with the BUNDY SA 01-006 R4 standard, under the following conditions:

Radiant heat source: 400° C.

Distance: 35 mm under the heat source

Dimensions of the heat box: 420 mm×420 mm×245 mm

Duration of the trial: 1 hour

Description of the thermocouples:

-   -   Internal thermocouple: Position of the thermocouple touching the         external surface of the ceramic cylinder, at the middle point of         the length (15 cm) and measuring the temperature on the inside         of the protective tube.     -   Ambient thermocouple: A thermocouple for the measurement of the         ambient temperature in the heat box.

During the trial all of the temperatures were recorded.

Delta T is calculated as the difference between the T of the transmitter and the T on the inside of the tube:

Delta T=transmitter T−internal T

The results of the trial are shown in the attached Table I.

TABLE I Time transmitter T internal T Delta T (min) (° C.) (° C.) ambient T (° C.) 0 23 23 24 0 2 129 64 78 65 4 264 81 96 183 6 291 77 87 214 8 316 83 93 233 10 329 87 98 242 15 363 98 109 265 20 384 105 119 279 25 394 107 128 287 30 396 109 130 287 35 398 110 135 288 40 400 109 139 291 50 400 116 143 284 60 400 118 152 282

In spite of the fact that reference has been made to a specific embodiment of the invention, it is clear for an expert in the subject matter that the protection tube described is capable of being used with numerous variations and modifications, and all of the details mentioned can be substituted for others that are technically equivalent, without departing from the scope of the protection defined by the attached claims. 

1. Open protective tube comprising a first layer (1) with a plurality of plastic threads which are woven to one another and a second layer of aluminium foil (2), and is characterised in that the said aluminium foil (2) comprises a plastic material film (3) and an aluminium film (4), said plastic material film (3) being welded to the stated first layer (1).
 2. Protective tube according to claim 1, characterised in that said plastic material film (3) is made from polyester.
 3. Protective tube according to with claim 1, characterised in that the threads that comprise said first layer (1) are made from polyester.
 4. Protective tube according to with claim 1, characterised in that the threads that comprise said first layer (1) are made from polyester and polyamide.
 5. Protective tube according to claim 1, characterised in that the aluminium foil (4) is located on the inside of the tube. 